D/A converters/decoders have a wide variety of applications in modern electronics. Typically, a D/A converter provides an analog output corresponding to a digital input.
Display elements in modern displays, for example, are formed as two dimensional arrays of emissive elements, typically in the form of liquid crystals, light emitting diodes (LEDs), organic light emitting diodes (OLEDs), plasma cells or the like, surface conduction electrode-emitter displays (SEDs). Emissive elements are arranged in a two-dimensional array. Each element represents one pixel in the array, and may include one or more active components. For example color liquid crystal displays (LCDs) typically include at least three crystals per pixel, with each crystal representing one color component of the pixel. The three crystals, in combination with back lighting form the emissive element that can be used to display a pixel of arbitrary color.
As each display is made of a multitude of individual display elements, suitable drive circuitry is required. As each display element is typically formed with three color emitting components, the drive circuitry typically includes three separate driver elements for each pixel. Drive circuitry typically includes multiple D/A converters, each of which includes a digital decoder used to output suitable analog drive voltages or currents to drive the individual display elements. Typical D/A decoders are formed using a multitude of transistor switches to provide output analog voltages selected in dependence on a digital value to be decoded. One such design uses a complementary metal oxide semiconductor (CMOS) switches, requiring at least two transistors per switch.
As newer displays are significantly thinner and lighter than conventional CRT displays, they may be miniaturized and form part of a variety of electronic devices including televisions, computer monitors, and easily portable devices such as digital media players, mobile phones, personal digital assistants, MP3 players, and the like. In such devices reducing transistor count is desirable, as reduced transistor counts reduce power consumption.
More generally, integrated circuits and functional blocks of such integrated circuits with fewer transistors may be manufactured to consume less power and occupy less space.
Accordingly, a digital to analog decoder having fewer electronic components is desirable.